Steric Influence on the Structure, Magnetic Properties, and Reactivity of Hexa- and Octaisopropylmanganocene
详细信息 查看全文
- 作者：Melanie L. Hays ; David J. Burkey ; Jason S. Overby ; Timothy P. Hanusa ; Scott P. Sellers ; Gordon T. Yee ; and Victor G. Young ; Jr.
- 刊名：Organometallics
- 出版年：1998
- 出版时间：December 7, 1998
- 年：1998
- 卷：17
- 期：25
- 页码：5521 - 5527
- 全文大小：112K
- 年卷期：v.17,no.25(December 7, 1998)
- ISSN：1520-6041
文摘
The reaction of KCpni (Cpni = (C3H7)nC5H5-n; n = 3, 4) with MnCl2 in THF produces themetallocenes (Cp3i)2Mn or (Cp4i)2Mn in good yield. Solid-state magnetic susceptibilitymeasurements indicate that orange-red (Cp3i)2Mn is in high-spin/low-spin equilibrium atroom temperature. In the solid-state, it has a centrosymmetric sandwich structure with anaverage Mn-C bond length (2.130(6) Å) typical of low-spin manganocenes. (Cp3i)2Mn reducestetracyanoethylene (TCNE) to generate the TCNE radical anion. Despite the presence ofadditional electron-donating isopropyl groups, pale yellow (Cp4i)2Mn is entirely high-spinfrom room temperature to 10 K. The crystal structure of (Cp4i)2Mn reveals a bent metallocenestructure, with a centroid-Mn-centroid angle of 167.4
and an average Mn-C distance of2.42(2) Å. This structure is consistent with its high-spin electron configuration; the longerMn-C bonds provide relief from the steric strain that would be present in a low-spin complex.The reaction of (Cp4i)2Mn with TCNE produces a tricyanovinylation product, C5(i-Pr)4HC(CN)=C(CN)2, which was characterized by X-ray diffraction.
and an average Mn-C distance of2.42(2) Å. This structure is consistent with its high-spin electron configuration; the longerMn-C bonds provide relief from the steric strain that would be present in a low-spin complex.The reaction of (Cp4i)2Mn with TCNE produces a tricyanovinylation product, C5(i-Pr)4HC(CN)=C(CN)2, which was characterized by X-ray diffraction.